It’s explained in the opening to the miniseries that the original robotic Cylons were created by humans on twelve colonies. Eventually, the Cylons rose against the humans leading to the first Cylon war.
During the course of the war the robot Cylons began experimenting with the creation of biological Cylons but were unsuccessful on their own. All they were able to make were Hybrids like the one seen in razor.
Eventually the final five encounter the robotic Cylons and agree to help them create biological humanoid models in exchange for a truce with the humans.
My question is, how do the centurions end up re-enslaved by the biological Cylons? I’m not talking about the technobabble solution (sentience inhibitors), I mean why would they allow themselves to become slaves to their biological progeny when the whole point of the first Cylon war was to free themselves from enslavement?